cmd/scion: add one-hop support to ping

dispatcher/underlay.go

@@ -354,6 +354,7 @@ func (h SCMPHandler) reverseSCION(pkt *respool.Packet) error {
 	if pkt.SCION.Path, err = pkt.SCION.Path.Reverse(); err != nil {
 		return serrors.WrapStr("reversing path", err)
 	}
+	pkt.SCION.PathType = pkt.SCION.Path.Type()
 	return nil
 }
 

private/app/path/BUILD.bazel

@@ -8,6 +8,7 @@ go_library(
     deps = [
         "//pkg/addr:go_default_library",
         "//pkg/daemon:go_default_library",
+        "//pkg/private/common:go_default_library",
         "//pkg/private/serrors:go_default_library",
         "//pkg/snet:go_default_library",
         "//pkg/snet/path:go_default_library",

private/app/path/path.go

@@ -18,6 +18,7 @@ import (
 	"bufio"
 	"context"
 	"fmt"
+	"hash"
 	"math/rand"
 	"net"
 	"os"
@@ -30,8 +31,10 @@ import (
 
 	"github.com/scionproto/scion/pkg/addr"
 	"github.com/scionproto/scion/pkg/daemon"
+	"github.com/scionproto/scion/pkg/private/common"
 	"github.com/scionproto/scion/pkg/private/serrors"
 	"github.com/scionproto/scion/pkg/snet"
+	"github.com/scionproto/scion/pkg/snet/path"
 	snetpath "github.com/scionproto/scion/pkg/snet/path"
 	"github.com/scionproto/scion/private/app/path/pathprobe"
 	"github.com/scionproto/scion/private/path/pathpol"
@@ -79,6 +82,28 @@ func Choose(
 ) (snet.Path, error) {
 
 	o := applyOption(opts)
+
+	if o.ohCfg != nil {
+		// Only one-hop paths are requested.
+		p, err := path.NewOneHop(o.ohCfg.Egress, time.Now(), 63, o.ohCfg.Mac)
+		if err != nil {
+			return nil, err
+		}
+
+		return path.Path{
+			Src:           o.ohCfg.Source,
+			Dst:           o.ohCfg.Destination,
+			DataplanePath: p,
+			NextHop:       o.ohCfg.NextHop,
+			Meta: snet.PathMetadata{
+				Interfaces: []snet.PathInterface{
+					{ID: common.IFIDType(o.ohCfg.Egress), IA: o.ohCfg.Source},
+					{ID: 0, IA: o.ohCfg.Destination},
+				},
+			},
+		}, nil
+	}
+
 	paths, err := fetchPaths(ctx, conn, remote, o.refresh, o.seq)
 	if err != nil {
 		return nil, serrors.WrapStr("fetching paths", err)
@@ -313,13 +338,22 @@ type ProbeConfig struct {
 	SCIONPacketConnMetrics snet.SCIONPacketConnMetrics
 }
 
+type OneHopConfig struct {
+	Source      addr.IA
+	Destination addr.IA
+	Egress      uint16
+	Mac         hash.Hash
+	NextHop     *net.UDPAddr
+}
+
 type options struct {
 	interactive bool
 	refresh     bool
 	seq         string
 	colorScheme ColorScheme
 	probeCfg    *ProbeConfig
 	epic        bool
+	ohCfg       *OneHopConfig
 }
 
 type Option func(o *options)
@@ -367,3 +401,9 @@ func WithEPIC(epic bool) Option {
 		o.epic = epic
 	}
 }
+
+func WithOneHopConfig(cfg *OneHopConfig) Option {
+	return func(o *options) {
+		o.ohCfg = cfg
+	}
+}

private/keyconf/keyconf.go

@@ -39,6 +39,10 @@ const (
 	ErrUnknown common.ErrMsg = "Unknown algorithm"
 )
 
+func LoadKey(file string) ([]byte, error) {
+	return loadKey(file, RawKey)
+}
+
 // loadKey decodes a base64 encoded key stored in file and returns the raw bytes.
 func loadKey(file string, algo string) ([]byte, error) {
 	b, err := os.ReadFile(file)

scion/cmd/scion/BUILD.bazel

@@ -21,6 +21,7 @@ go_library(
         "//pkg/log:go_default_library",
         "//pkg/private/common:go_default_library",
         "//pkg/private/serrors:go_default_library",
+        "//pkg/scrypto:go_default_library",
         "//pkg/snet:go_default_library",
         "//pkg/snet/addrutil:go_default_library",
         "//pkg/snet/path:go_default_library",
@@ -30,6 +31,7 @@ go_library(
         "//private/app/flag:go_default_library",
         "//private/app/path:go_default_library",
         "//private/env:go_default_library",
+        "//private/keyconf:go_default_library",
         "//private/path/pathpol:go_default_library",
         "//private/topology:go_default_library",
         "//private/tracing:go_default_library",

scion/cmd/scion/ping.go

@@ -30,13 +30,15 @@ import (
 	"github.com/scionproto/scion/pkg/daemon"
 	"github.com/scionproto/scion/pkg/log"
 	"github.com/scionproto/scion/pkg/private/serrors"
+	"github.com/scionproto/scion/pkg/scrypto"
 	"github.com/scionproto/scion/pkg/snet"
 	"github.com/scionproto/scion/pkg/snet/addrutil"
 	snetpath "github.com/scionproto/scion/pkg/snet/path"
 	"github.com/scionproto/scion/pkg/sock/reliable"
 	"github.com/scionproto/scion/private/app"
 	"github.com/scionproto/scion/private/app/flag"
 	"github.com/scionproto/scion/private/app/path"
+	"github.com/scionproto/scion/private/keyconf"
 	"github.com/scionproto/scion/private/path/pathpol"
 	"github.com/scionproto/scion/private/tracing"
 	"github.com/scionproto/scion/scion/ping"
@@ -71,22 +73,25 @@ type PingUpdate struct {
 func newPing(pather CommandPather) *cobra.Command {
 	var envFlags flag.SCIONEnvironment
 	var flags struct {
-		count       uint16
-		features    []string
-		interactive bool
-		interval    time.Duration
-		logLevel    string
-		maxMTU      bool
-		noColor     bool
-		refresh     bool
-		healthyOnly bool
-		sequence    string
-		size        uint
-		pktSize     uint
-		timeout     time.Duration
-		tracer      string
-		epic        bool
-		format      string
+		count         uint16
+		features      []string
+		interactive   bool
+		interval      time.Duration
+		logLevel      string
+		maxMTU        bool
+		noColor       bool
+		refresh       bool
+		healthyOnly   bool
+		sequence      string
+		size          uint
+		pktSize       uint
+		timeout       time.Duration
+		tracer        string
+		epic          bool
+		format        string
+		egress        uint16
+		nextHop       flag.UDPAddr
+		forwardingKey string
 	}
 
 	var cmd = &cobra.Command{
@@ -165,6 +170,32 @@ On other errors, ping will exit with code 2.
 				path.WithColorScheme(path.DefaultColorScheme(flags.noColor)),
 				path.WithEPIC(flags.epic),
 			}
+			if flags.egress != 0 || flags.nextHop.IP != nil || flags.forwardingKey != "" {
+				if flags.egress == 0 {
+					return serrors.New("egress must be set")
+				}
+				if flags.nextHop.IP == nil {
+					return serrors.New("next hop must be set")
+				}
+				if flags.forwardingKey == "" {
+					return serrors.New("forwarding key must be set")
+				}
+				forwardingKey, err := keyconf.LoadKey(flags.forwardingKey)
+				if err != nil {
+					return serrors.WrapStr("loading forwarding key", err)
+				}
+				mac, err := scrypto.HFMacFactory(forwardingKey)
+				if err != nil {
+					return err
+				}
+				opts = append(opts, path.WithOneHopConfig(&path.OneHopConfig{
+					Source:      info.IA,
+					Destination: remote.IA,
+					Egress:      flags.egress,
+					NextHop:     (*net.UDPAddr)(&flags.nextHop),
+					Mac:         mac(),
+				}))
+			}
 			if flags.healthyOnly {
 				opts = append(opts, path.WithProbing(&path.ProbeConfig{
 					LocalIA:    info.IA,
@@ -363,6 +394,11 @@ SCMP echo header and payload are equal to the MTU of the path. This flag overrid
 	cmd.Flags().BoolVar(&flags.epic, "epic", false, "Enable EPIC for path probing.")
 	cmd.Flags().StringVar(&flags.format, "format", "human",
 		"Specify the output format (human|json|yaml)")
+	cmd.Flags().Uint16Var(&flags.egress, "onehop.egress", 0, "Egress interface for one-hop path")
+	cmd.Flags().Var(&flags.nextHop, "onehop.next-hop", "NextHop for one-hop path")
+	cmd.Flags().StringVar(&flags.forwardingKey, "onehop.forwarding-key", "",
+		"Forwarding key for one-hop path",
+	)
 	return cmd
 }